Water containing wax-based product

ABSTRACT

The present invention relates to a wax-based composition comprising at least about 0.5-30% water in a water-in-oil emulsion, wherein water is encapsulated in a lamellar lipid vesicle capable of withstanding wax melting point temperatures. The composition is useful in delivering water soluble actives in an anhydrous base, and is particularly well-adapted for uses in lipsticks and lip-care products.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Ser. No. 08/864,162,filed May 28, 1997, now U.S. Pat. No. 6,039,960, the contents of whichis incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to cosmetic and/or therapeutic products.In particular, the invention relates to wax-based products containingwater in the formulation.

BACKGROUND OF THE INVENTION

In recent years, lipstick has gone beyond the point of serving the solefunction of coloring the lips. Consumers are no longer satisfied with aproduct which serves a simple cosmetic purpose; rather, the demand isnow for a product which, in addition to providing an attractiveappearance, goes on smoothly, lasts all day, and also moisturizes andimproves the condition of the lips. The goals of moisturizing andconditioning have proven particularly difficult when using standardlipstick formulations.

Traditional lipsticks have primarily been anhydrous, i.e., they havebeen composed principally of hydrophobic waxes and oils. Such productshave relied on the formation of a thick occlusive film on the lips toprevent moisture loss. While to a large extent very effective inpreventing water loss, such anhydrous systems are unable to achieve themore desirable end of actively reconstituting the lips' lipid barrier orattracting and binding water to the lip surface. This is largely becausethe low polarity and high viscosity which characterize the typical waxycomponents, act as a barrier to active product diffusion. Moreover,these viscous materials frequently result in a product that leaves anundesirable greasy or waxy feeling on the lips.

Notwithstanding the problems which arise with their use, the hydrophobicwaxes and oils are an essential part of virtually any lipstick, in thatthey confer the solid physical structure required for ease ofapplication. It has been recognized that the availability of awater-containing lip product would obviate many of the problemsassociated with the anhydrous systems. For example, many of thetherapeutic or conditioning actives which would be useful in barrierrepair or moisture attraction are water soluble. ideally, the use of awater-in-oil emulsion system would provide the combination of featureswhich would both confer both occlusive film-forming properties andstructural integrity to the stick while still permitting delivery of thewater soluble and/or water attracting actives to the lips. Nonetheless,the cosmetics industry has, to date, produced few such systems. In part,the difficulty arises in the inherent incompatibility of water with thelow polarity waxes and oils; however, there are also serious problemswith loss of water from the stick during storage, and the lack ofstability of the water soluble actives in such a system. Generallyspeaking, the available systems rely entirely on the use of emulsifiers(see e.g., U.S. Pat. No. 5,342,134) to stabilize the contained actives.Since the trend in cosmetics is away from the use of emulsifiers,however, it would be preferable to design a water-in-oil emulsion systemwhich does not rely solely on standard emulsifiers for stability ofactives contained therein.

Therefore, there continues to be a need for a water-containing lipproduct which can moisturize and protect the lips, deliver stable watersoluble actives without the use of large amounts of standard emulsifiersor surfactants, and which is not susceptible to rapid loss of water fromthe mass. The present invention provides such a product, and solves manyof the problems encountered with other water-containing lip products.

SUMMARY OF THE INVENTION

The present invention relates to a wax-based composition comprising atleast about 0.5-30% water in a water-in-oil emulsion, wherein water isencapsulated in a lamellar lipid vesicle capable of withstanding thetemperatures encountered in a hot-pour process, i.e., wax or wax-likematerials' melting point temperatures. By “wax-based” is meant a productwhich contains over 5% by weight, more preferably over 10%, of wax or awax-like product in the formulation. The vesicle preferably has wallscomprising at least one high melting point polyoxyethylene fatty acidether, which confers the high temperature stability required for pouringlipstick or other wax-based products. The products so prepared losewater at a slower rate than other water-containing lip products, and arecapable of maintaining the stability of water soluble actives containedwithin the vesicle. In a preferred embodiment, the wax base is designedto contain several products with a relatively moderate to high level ofpolarity, so as to enhance compatibility with the water-containingvesicle.

DETAILED DESCRIPTION OF THE INVENTION

The use of lamellar vesicles to encapsulate and deliver both cosmeticand pharmaceutical actives has now long been established. In brief,these vesicles comprise one or more lipid layers, each surrounding asmall aqueous volume. Such vesicles and methods of making same have beendescribed in, for example, U.S. Pat. Nos. 4,895,452, 4,855,090,4,911,928, 4,917,951, 4,942,038, 5,000,960, 5,013,497, 5,023,086,5,032,457, 5,104,736, 5,147,723, 5,160,669, 5,213,805, 5,219,538,5,234,767, 5,256,422, 5,260,065, 5,405,615, 5,439,967, and 5,474,848.The contents of each of these is incorporated by reference in itsentirety. This type of vesicle is widely recognized as facilitatingdelivery of a number of different types of actives to a desired targetsite. A particularly useful type of lamellar vesicle for the presentpurpose is one which is primarily non-phospholipid in nature. Suchvesicles can be made from a wide variety of different components, as canbe readily discerned from the cited references. A typical example of thecomponents of an appropriate vesicle are, for example, a sterol, such ascholesterol; one or more surfactants (for example, fatty acids, fattyalcohols, and ethoxylated derivatives thereof, or sorbitan derivatives),and other oils or lipids. However, such vesicles have not previouslybeen used in lipsticks, as the most commonly used components of thevesicle wall typically have a temperature stability maximum of about 50°C.; therefore, the vesicles cannot withstand the high temperaturerequired in the preparation of lipsticks, or other hot-pour products.

It has now been determined that the use of an polyoxyethylene fattyethers having a melting point greater than that of the waxes being usedis adequate to stabilize the other more heat labile components of thevesicle. Preferably, the combined wall materials, including the ether,overall have a melting point at least 2° C. above that of the waxes orwax-type products being used in the hot-pour. Using a lipstick as anexemplary wax-based product, the melting point of the ether ispreferably at least about 80° C., preferably at least about 90° C., andmore preferably at least about 100° C. The ether is present in an amountof from about 0.01-8%, preferably from about 0.1-5%, and more preferablyform about 0.5-4%. Preferred compounds of this type include long chain(i.e., at least C20) polyethylene glycol ethers of a mixture of fattyalcohols with an average of at least 3 moles of ethylene oxide.Particularly preferred are such alcohols having a chain length of atleast C40, and an average of 3 moles of ethylene oxide, for example,C40-C60 pareth-3.

The remaining components of the vesicle can be any of those which arestandard in the art, as noted above. In particular, vesicle componentsare described in detail in the U.S. Patent documents listed above, whichare incorporated by reference herein. In a preferred embodiment, thelipid layer of the vesicle comprises, in addition to the high meltingpoint ether, a least one other standard polyoxyethylene fatty acidether, for example polyoxyethylene (n) cetyl, stearyl, oleyl, orlinoleyl ethers, wherein the average n value can be from 2-10. Otherstandard surfactants can also be incorporated into the lipid portion.Preferably, the lipid portion also comprises a sorbitan derivativesurfactant, for example, polyoxyethylene sorbitan fatty acidesters(TWEEN, ICI). The lipid layer will also comprise a steroidcomponent. This is preferably a sterol, for example cholesterol or anyother sterol with similar chemical properties. In a preferredembodiment, the sterol is a phytosterol, for example, soy sterol, or aphytosterol containing material, such as avocadin.

The lipid layer will also contain any other lipophilic material, e.g.,lipophilic emollients, which may be useful for the intended end use ofthe product. Lipophilic actives may be added to the lipid phase of thevesicle, provided they are stable at the high temperatures at which theproduct is prepared. In preparation of the vesicle, all lipophilicmaterials are combined into a single lipophilic phase. The aqueous phaseis prepared separately, and comprises water, preferably in an amount offrom about 0.5-70% of the vesicle mixture as a whole, and anyhydrophilic material which is desired to be incorporated into theproduct as a whole; examples of such include, water solublepreservatives and antioxidants; water soluble actives or skinconditioning agents, for example, humectants, such as hyaluronic acidsalts, hydrogels, or glycerol or elastin; collagen; alpha andbeta-hydroxy acids; or milk protein. The determination of proportions ofthe individual components, including actives, of the two phases isreadily made by the skilled artisan in accordance with the standardusage in the art. It will be noted that the amounts of each componentemployed in the vesicle are not especially crucial, and ratios for thecomponents may be varied, as described, for example, in U.S. Pat. Nos.5,260,065 and 5,256,422. In the final stage of preparation, theindividual phases are combined under high shear, using methods wellknown in the art, to form lamellar lipid vesicles suspended in acontinuous aqueous phase, which is then ready for incorporation into thewax base.

The preparation of the lamellar vesicle solves the problem of providinga stable vehicle for water and water soluble actives. However, it isthen necessary to incorporate this highly aqueous vehicle into astrongly hydrophobic wax base. As noted above, a water-in-oil emulsionis in principle the preferred vehicle for providing ease of applicationcombined with the necessary moisturizing but non-greasy properties theconsumer desires; however, in practice, the preparation of an appealing,effective and stable solid water-in-oil emulsion has been difficult. Ithas been surprisingly found, however, that a hydrophobic wax base whichaccommodates a large percentage of water, with the use of a very smallamount of emulsifier, can be obtained.

An anhydrous waxy base constitutes the oil component of the water-in-oilemulsion, and typically comprises at least one wax, one oil, and oneemulsifier. The anhydrous base constitutes from about from about70-99.5% of the total wax based product. The wax component of theanhydrous base contains any one or a combination of cosmetically orpharmaceutically acceptable waxes in an amount of from about 10-40% ofthe total anhydrous base, and greater than 5%, preferably about 10% toabout 30% by weight of the total wax-based product. In the context ofthe present invention, the term “wax” will be understood to encompassany organic component that is solid at room temperature, which componentcan be used to solidify the liquid components of the product when allare heated together, then cooled to room temperature. This definitionincludes waxes in the traditional sense, i.e., those plant, animal ormineral waxes containing primarily esters of higher fatty acids andalcohols, free higher acids and alcohols, and saturated hydrocarbons;examples of such traditional waxes include, but are not limited to,carnauba wax, candelilla wax, beeswax, synthetic wax, shellac wax,spermaceti, lanolin wax, ozokerite, bran wax, ceresin wax, bayberry wax,paraffin, rice wax and jojoba wax. However, it also includes othernon-traditional wax-like materials, including, but not limited to,various fatty alcohols, fatty acids, fatty esters, polyethylenes,polyethylene glycols, and sterols as well as synthetic resinous productshaving a wax-like, i.e., hard, brittle, relatively non-greasy, texture,such as silicone waxes.

The oil portion of the anhydrous base preferably includes one or morecosmetically acceptable oils or oil-like emollients. Any cosmetically orpharmaceutically acceptable oil may be used in the wax base, theselection being made to some extent upon the desired viscosity of thefinal product. Examples of suitable oils or oil-like emollients can befound in the International Cosmetic Ingredient Handbook, CTFA, 1996, thecontents of which are incorporated herein by reference. Useful materialsinclude, but are not limited to, castor oil, coconut oil, corn oil,jojoba oil, cottonseed oil, soybean oil, walnut oil, wheat germ oil,sunflower seed oil, palm kernel oil, calendula oil, C10-18triglycerides, lanolin and lanolin derivatives, illipe butter, sheabutter; esters having the formula RCO—OR' wherein RCO represents acarboxylic acid radical and OR' represents an alcohol residue, such asisodecyl neopentanoate, tridecyl octanoate, cetyl palmitate, cetyloctanoate, cetyl stearate, cetyl myristate, isopropyl palmitate,isopropyl myristate, polyglyceryl-2-isostearate, neopentyl glycoldistearate, isodecyl oleate, decyl isostearate, diisopropyl sebacate,PEG-4 diheptanoate, dioctyl malate, and isohexyl neopentanoate; fattyalcohols, such as lanolin alcohol or oleyl alcohol; and silicone oils,such as cyclomethicone, dimethicone, cetyl dimethicone, lauryltrimethicone, and dimethiconol. The oil component comprises from atleast about 30-80% of the anhydrous component, and from about 20-70%,more preferably about 50-70%, of the total weight of the wax-basedproduct. In a particularly preferred embodiment, at least half of theoil component is made up of one or more polar oils. Preferably, at leastabout 25%, more preferably at least about 30%, most preferably at leastabout 40-50%, and up to 70%, of the wax based product as a whole is madeup of one or more polar oils, which are more compatible with water andaid in maintaining the stability of the product. A polar oil is anon-hydrocarbon oil, particularly one which contains alcohol residues,or an ester or triglyceride component. Examples of useful polar oilsinclude but are not limited to vegetable oils, such as jojoba oil, sheabutter, almond oil, peach kernel oil, sesame seed oil and the like; andfatty esters, such as neopentyl glycol dicaprate, orpolyglyceryl-2-diisostearate. The oil component can comprise one or anycombination of these polar oils

To prepare an emulsion of the anhydrous base with an aqueous component,an emulsifier having an HLB of 7 or less is employed. From about 0.5-5%,more preferably from about 0.5-3%, of the wax-based product as a wholeis emulsifier, which may be a part of the anhydrous base, orincorporated separately. In a preferred embodiment the emulsifier has anHLB of from about 5-7. It is particularly preferred that a non-ionicemulsifier be employed. Examples of such emulsifiers can be found inMcCutcheons Emulsifiers and Detergents, the contents of which areincorporated herein by reference. Particularly preferred emulsifiers aresorbitan sesquioleate, and PEG-7 hydrogenated castor oil. Although theemulsifier can be used in an amount of up to about 5% of the totalweight of the composition, it has been surprisingly found that as littleas 1-2% provides a very stable water-in-oil emulsion. This isparticularly unexpected when a large quantity of water, e.g., 5% ormore, is being employed, and provides a particular advantage in that thepotential for irritation is significantly reduced by the presence ofvery low level of emulsifier in the product.

The wax base may also comprise other optional components, depending onthe intended end use and form of the final product. For example, for acolored lipstick product, one or more pigment compounds will be added.The pigment may be any that are cosmetically acceptable for use in a lipproduct. These include both inorganic and organic compounds, forexample, inorganic metallic oxides, mica, bismuth oxychloride, or D&Cand FD&C dyes. If used, the pigment is generally employed at a level offrom about 0.5-15%.

The vesicular component, when prepared as described above, is also addedto the wax base, in an amount sufficient to provide about 0.5-30% waterin the final formulation, preferably about 1-10%, more preferably about4-8%, water. It will be understood that a portion of the waterincorporated into the wax base with the vesicular component is notencapsulated, but is instead part of the continuous aqueous phase inwhich the vesicles are suspended. Alternately, in place of the vesicles,water alone can be added directly to the wax base, in an amount of fromabout 0.5-20% of the total formulation.

The final product may also benefit from the addition of a small quantitye.g., from about 0.01-1%, of a high melting point polyethylene to theformulation. The addition of this material aids in water retention,making the base less porous, and also aids in dispersion of the watercomponent throughout the product. Polyethylene also can add to thestructural integrity of a solid stick product, aiding in preventingbreakage.

Biologically active materials which are lipid compatible can also beadded directly to the wax base. These actives may be any which areappropriate for the intended end use of the product and the target areato which the product is to be applied; for example, the base can containlipophilic treatment or conditioning materials such as Vitamin E andderivatives, Vitamin A and derivatives, lipophilic antioxidants,emollients such as petrolatum or dimethicone, long-chain alpha hydroxyacids, ceramides, or skin lipids to enhance barrier function. Thoseskilled in the art will recognize that for either the lipid or theaqueous phase, other actives for topical application can be chosen fromanalgesics, anesthetics, anti-acne agents, antibacterials, antiyeastagents, antifungal agents, antiviral agents, antidandruff agents,antidermatitis agents, antipruritic agents, antiemetics, antimotionsickness agents, anti-inflammatory agents, antihyperkeratolytic agents,anti-dry skin agents, antiperspirants, antipsoriatic agents,antiseborrheic agents, hair conditioners and hair treatment agents,antiaging agents, antiwrinkle agents, antiasthmatic agents andbronchodilators, sunscreen agents, antihistamine agents, skin lighteningagents, depigmenting agents, wound-healing agents, vitamins,corticosteroids, tanning agents, or hormones. It is a routine matter todetermine into which phase of the wax-based product the active is mostconveniently incorporated.

Preservatives may also be employed, in an amount of from 0.01-5%,preferably from 0.01-1%, of the formula weight. Examples of suitablepreservatives are BHA, BHT, propyl paraben, or methyl paraben.

It will be understood that, although the product of the presentinvention has been exemplified in the form of a lipstick, theformulation can be applied not to only lipsticks in a cosmetic sense,but to any wax-based product intended for topical or parenteralapplication of treatment or conditioning materials. Additional examplesinclude, but are not limited to, a stick product to be used as a lipbalm, for application of pharmaceutical products to the lip area, apot-contained lip product, a deodorant stick, or any waxy product whichis intended to deliver cosmetic or pharmaceutical actives. Additionalembodiments of the present invention will be readily apparent to thoseskilled in the art. The invention is further illustrated by thefollowing non-limiting examples.

EXAMPLES Example 1

The following describes the preparation of a lamellar vesicle for use inthe lip product

MATERIAL WEIGHT % Glyceryl distearate 5.0 Stearyl alcohol 0.4Steareth-10 3.0 PEG-soy sterol 2.0 C40-C60 pareth-3 3.0 Polysorbate 802.0 Castor Oil 20.0  Deionized water QS Disodium EDTA 0.1

All ingredients except the deionized water and EDTA are combined in ajacketed support kettle to form the lipophilic phase, heated to 95-100°C. under propeller agitation, and mixed until clear. The remainingingredients are combined and heated to about 70-75° C. The lipophilicphase is forcibly injected, by way of a three-way stopcock, into theaqueous phase in a 25 ml syringe. The mixture is then forced into asecond syringe at a flow-rate of 8-12×10² cm/sec through a 1 mm orifice,and then continuously driven between the two syringes for about twominutes, resulting in a milky suspension containing the lipid vesicles.

Example 2

The following formulation shows a solid lip product prepared inaccordance with the present invention:

MATERIAL WEIGHT % Phase 1 Polyethylene 0.25 paraffin 1.50 ceresin 1.50neopentyl glycol dicaprate 0.50 polyglyceryl-2-triisostearate 0.50 Phase2 refined jojoba oil 10.00  shea butter 4.00 candelilla wax 1.00 Phase 3castor oil 28.50  carnauba wax 1.50 candelilla wax 2.50 ozokerite 1.75beeswax 2.50 oleyl oleate 5.00 Polydecene 1.50 sorbitan sesquioleate1.20 isodecyl neopentanoate 0.25 Phase 4 BHT 0.20 propyl paraben 0.05Vitamin E 0.15 Phase 5 pigment 11.00  castor oil 17.00  Phase 6multilamellar vesicles 8.15 (as prepared in Example 1)

Phase 1 materials are combined, and heated to 90° C. under 150-200 RPMmixer. The components are mixed until they are completely dissolved andthe phase is clear and homogeneous. Once this is achieved, the phase iscooled to 850° C.

Phase 2 materials are added to Phase 1 at 85° C. under continuous150-200 RPM mixer agitation, until the mixture is clear and homogeneous.

Phase 3 materials are added to the Phase 1 and 2 mixture at 85° C. undercontinuous agitation until the phase 3 materials are dissolved and themixture is homogeneous.

Phase 4 materials are added to the already combined phases at 85° C. andmixed until the mixture is homogeneous. While maintaining the sametemperature, the sequence 5 materials are combined with the mixture andmixed until the mixture is uniform. The phase 6 materials are added veryslowly and carefully to the existing mixture. Mixing is continued at200-250 RPM until all air bubbles disappear, then mixing is slowed downto 100-150 RPM. When the batch is completely uniform, it is cooled to80° C., then mixed for another 10-15 minutes. The product is then pouredinto a mold at 80° C.

What we claim is:
 1. A wax-based composition comprising at least about0.5-30% water in a water-in-oil emulsion, wherein water is encapsulatedin a lamellar lipid vesicle capable of withstanding wax melting pointtemperatures.
 2. The composition of claim 1 wherein the vesiclecomprises at least one high-melting point polyoxyethylene fatty ether.3. The composition of claim 2 wherein the ether has a melting point ofat least about 80° C.
 4. The composition of claim 2 wherein the etherhas a melting point of at least about 90° C.
 5. The composition of claim2 wherein the ether has a melting point of at least about 100° C.
 6. Thecomposition of claim 2 wherein the ether has a chain length of at leastC20.
 7. The composition of claim 2 wherein the ether has a chain lengthof at least C40.
 8. The composition of claim 1 wherein the water-in-oilemulsion comprises greater than 5 to about 30% by weight of one or morewaxes.
 9. The composition of claim 8 which comprises an emulsifierhaving an HLB of about 7 or less.
 10. The composition of claim 9 whereinthe emulsifier has an HLB of from about 5 to about
 7. 11. Thecomposition of claim 10 wherein the emulsifier is nonionic.
 12. Thecomposition of claim 11 wherein the emulsifier is sorbitan sesquioleate.13. The composition of claim 8 wherein the emulsifier is present in anamount of from about 1-2%.
 14. The composition of claim 8 whichcomprises from about 20-70% of one or more oils.
 15. The composition ofclaim 14 which comprises at least about 50% of one or more polar oils.16. The composition of claim 1 in which the vesicle also comprises atleast one water soluble active component.
 17. An anhydrous lipstick basecomprising from at leastl10-40% waxes, from at least 30-80% oils, and anemulsifier, wherein at least 50% of the oil comprises one or more polaroils.
 18. The base of claim 17, wherein the polar oil is a vegetable oilor a fatty ester.
 19. The base of claim 17, wherein the emulsifier is anon-ionic emulsifier having an HLB of 7 or less.
 20. The base of claim17, wherein the emulsifier is present in an amount of from about 2-10%.21. A cosmetic or pharmaceutical wax-based composition which is awater-in-oil emulsion, the emulsion comprising at least about 50% polaroils, from about 10-30% waxes, from about 0.5-5% emulsifier, and about0.5-30% water.
 22. A cosmetic or pharmaceutical composition forapplication to the lips comprising, in a water-in oil emulsion, fromabout 0.5-30% water, wherein water is encapsulated in a lamellar lipidvesicle which comprises at least one high-melting point polyoxyethylenefatty ether, and from 10-30% waxes, from 40-70% oils, and from 0.5-5%emulsifier, wherein at least about 50% of the composition as a wholecomprises one or more polar oils selected from the group consisting ofvegetable oils, triglycerides, fatty esters, or mixtures thereof. 23.The composition of claim 22, wherein the ether has a melting point offrom at least about 80° C. to at least about 100° C.
 24. The compositionof claim 22 wherein the ether has a chain in length of at least C20. 25.The composition of claim 23 wherein the ether is C40-C60 pareth-3. 26.The composition of claim 22 wherein the emulsifier is a non-ionicemulsifier having an HLB of 7 or less, and is present in an. amount offrom about 1-2% by weight of the total composition.
 27. The compositionof claim 26 wherein the emulsifier is sorbitan sesquioleate.
 28. Thecomposition of claim 22 which also comprises from 0.01-1% polyethylene.29. The composition of claim 22 wherein the vesicle comprises at leastone water soluble active.
 30. The composition of claim 22 whichcomprises from about 5-10% water, from about 10-20% waxes, from about50-70% polar oils, from about 1-2% emulsifier, from about 0.1-1%polyethylene, and to at least one water soluble active.
 31. A method ofdelivering water soluble actives to the skin comprising applying to theskin the composition of claim 1 into which the actives have beenincorporated.